Violence is the expression of physical force against self or other, compelling action against one's will on pain of being hurt.
Culture is an integrated pattern of human knowledge, belief, and behavior that depends upon the capacity for symbolic thought and social learning.
A spree killer, also known as a rampage killer, is someone who embarks on a murderous assault on his victims in a short time in multiple locations.
Mass Murder is the act of murdering a large number of people, typically at the same time or over a relatively short period of time.
Murder is the unlawful killing of another human being with intent.
Desensitization is to make (an individual) nonreactive or insensitive to a stimulus.
Addiction is a state in which the body relies on a substance for normal functioning and develops physical dependence.
A gang is a group of people who through the organization, formation, and establishment of an assemblage share a common identity, in this sense, as criminals.